Low back pain is the second most common reason for visiting a physician in the United States. Most causes of low back pain are of mechanical etiology: low dorsal, dorso-lumbar, lumbar, lumbo-sacral, intervertebral disc compression, herniation, and degenerative disease; low dorsal, dorso-lumbar and lumbar inter-vertebral facet ligamentous strain and arthritis; inter-vertebral and vertebro-iliac ligamentous sprains; low dorsal and lumbar musculo-tendinous strains, as well as low dorsal and lumbar fractures. Low back pain of non-mechanical etiology is not relieved by lumbar traction.
The pathogenesis of mechanical low back pain involves the force of weight of the upper body acting upon the low back during the erect position. Acute or repeated excessive weight bearing is often the precipitating factor. Frequently the main thrust of the weight bearing force is to one side, with the result that low back pain is commonly felt to one side. The usual manner of action of the traumatic force is by a flexion force of the low back, with resultant pathology of compression of the anterior elements of the lower back complex (anterior portions of intervertebral discs, of vertebrae), and of traction of the posterior elements (posterior annulus fibrosus of inter-vertebral discs, intervertebral ligaments, musculo-tendinous junctures).
Lumbar traction has been used since prehistoric times in the treatment of spinal disorders, and is to this day an accepted mode of therapy for mechanical low back pain. This is effected in the horizontal position, usually supine; the traction force being a cord attached to a pelvic belt from the foot of a bed or table, acting against the weight of the upper body. Frequently, the foot of the bed or table is raised to increase the physical moment of the traction force upon the low back. Experimental studies of pelvic traction have demonstrated that traction produces significant widening of the intervertebral space. Epidermal injection of contrast medium was used to outline the posterior aspects of the lumbar discs. This technique has shown that the separation of lumbar vertebrae by traction was significant when disc prolapse was present, and that traction reduced the extent of lumbar disc prolapse. A number of studies have been made to evaluate the clinical benefit of this mode of physiotherapy. It has been found that in patients suffering of low back pain, a group treated with pelvic traction showed significantly greater improvement than a group given conventional treatment, and than a group given no treatment. It has also been found in patients suffering of low back pain and sciatica that lumbar traction nearly always relieved pain while the patient was on treatment. However, the benefit did not last, perhaps because of physical activity between sessions.